1. Field of the Invention
The present invention relates to the art of automatic painting using an industrial robot, and more particularly to an improved automatic painting system for painting various parts.
2. Description of the Prior Art
Conventional automatic painting systems have painting devices and other devices placed in a closed painting booth in which an operator controls the devices to paint parts. The painting system therefore has required an explosion-proof arrangement for preventing an explosion, for some reasons, of a mist of paint having entered the devices in the painting booth. The painting system has also required an air conditioning unit such as an air curtain for blocking the paint mist against entry to make operator's environment more safe and comfortable. However, it has been difficult and costly to render every device in the painting booth resistant to explosions. Where the air curtain is employed for providing better operator's environments, air flows around the parts being painted are disturbed by the air curtain to thereby lower the efficiency with which the parts are painted. Furthermore, the air curtain has proven insufficient as a adequate means for improving the operator's environments. With the air curtain, a considerable quantity of air has to be supplied for keeping the environment better suited for the operator as well as for maintaining a desired quality of painting, and the cost of energy needed for supplying such a large amount of air is high. Another problem with the prior painting system is that the painting booth takes up a large space for accommodating the devices and the operator therein. The operator in the working space within the booth wears gloves and a mask which are a source of dust particles to be trapped in the coated paint layer resulting in a poor quality of painted parts. Where a robot continuously operable in a three-dimensional space is installed in the painting booth for automatic paint spraying, such robot comprises an explosion-proof hydraulically-operated robot, which however is large in size and consumes an increased amount of electric power. Thus, such a robot-operated painting system is expensive.